Reciprocating pump



Jan. 9, 1962 H. HoRLAcHER RECIPROCATING PUMP Filed July 2, 1959 N m mm .s mn Y mm E wo N M 7H R M W f ITIKMMPIIFWWWWVVFJMMVL. IIJ 1 n I .m l m m m m Llwuul |L.|||H .l|| r| 4 I I l l I l I l I l l I l I l l l I I l l I l Il' lfl m Q .munmm United States Patent C 3,016,016 RECIPROCATING PUMP Herman Horlacher, Cincinnati, Ohio, assignor to The Cincinnati Milling Machine. Co., Cincinnati, IOhiO, a corporation of'Ohio Filed July 2, 1959, Ser. No. 824,593

. 3 Claims. (Cl. 103-48) y The present invention relates to self-reciprocating pumps such as scavenge pumps.

In the present invention a self-reciprocating piston type pump is provided which is particularly suited for use as a sca-venge pump in a hydraulically operated machine tool. In a typical hydraulic system yfor aY machine tool uid from a sump is delivered under pressure by a pump to a pressure line connected to the hydraulically operated mechanisms of the machine, and is returned to the sump. However, some of the circulating uid inevitably leaks out of this system, which lluid can generally be collected in reservoirs provided in the machine tool. The pump of the present invention can be connected to the pressure line of the machine hydraulic system and will operate continuously, `with minimum tendency to stall, to return escaped fluid from a reservoir to the sump.

It is therefore a general object of the present invention to provide an improved reciprocating pump operable continuous from a source 'of pressure With tendency to stall.

l-t is another object of the present invention to provide a piston scavenge pump operable to pump uid on each stroke.

It is yet another objectof the presentinvention to provide a piston type scavenge pump operable from a pressure source having positive lacting means to reverse the valve `alternately supplying pressure to the driving pistons.

It is yet another object of the present invention to pro-V vide a scavenge pump which can be utilized to pump fluid continuously from one reservoin'or alternately from twov reservoirs.

It is still another object to prov-ide a simple, effective, scavenge pump operable to pump a large quantity of iluid in relation to the fluid utilized; and which is self-starting and will operate continuously without stalling.

Other objects and advantages of the present invention should be readily apparent by reference to the following specication, considered in conjunction with the accompanying drawings forming a part thereof, and it is to be 'V understood that any modilications may be made in the exact structural details ythere shown `and described, within the scope of the appended claims, without departing from or exceeding the Vspirit of the invention.

In the drawings: FIG. l is an elevational view, partly in cross-section, of the scavange pump of the present invention;

FIG. 2 is a view taken on line 2 2 of -FIGL l; FIG. 3 Ais a view taken Online 3-i3 of FIG. 1; and

FIG. 4 shows a modification to the pump to permit drawing fluid from two reservoirs.

The scavenge pump 10 has a bodyllhaving a bore 12 extending therethrough. In eachend of fthe bore 12 there is snugly received a'cylindrica-l core 13 having `a central bore 14. rIihe bores 14'areclosedat their outer ends by the end plates 8 and 9 connectedfto the sides of the 4body 1-1. The bores 14 rdefiney spaced motor chambers A15 and I16 md slidably receive pistons 17 and 18, re-

in spaced relation to a common piston rod 19. f

The motor chamber 15 has at its left y(as viewed in FIG. 2), or outer, end laniulet port 20 and spaced from its right, or inner, end an inletport 21. The other motor spectively, therein. The pistons 17 and 18 are connected chamber 16 also has an inlet'polt 22 at its outer, end

an outlet port 23 spaced from its inner end. It will be noted that the ports of motor chamber `16 are in opposed relation to the ports of chamber I15 wth the inlet pont l22 at the right end of the chamber instead of the left end, and the outlet port 23 spaced from the left end thereof instead of the right end. 'Ille piston rod -19 andthe pistons 17 and y18 thereon reciprocate between an extreme left hand posit-ion (as shown in FIG. 2) Where the outlet port 23 of chamber 16 is uncovered by piston 118 and therefore is connected to inlet port 22 through chamber 16, and an extreme right hand position where outlet port 21 of chamber 15 is uncovered by piston L17 and thereby connected to inlet port 20.

The bore 12 and the inner ends of cores 13 dene a vacuum, or pump, chamber 24 between the motor chambers. Piston 25, connected to piston rod 19 and reciprocated thereby, isV slidably received' in the vacuum chamber. The vacuum chamber 24 has `an inlet port, v26 Yand 27, at each end (see FIG. l), and has an outlet port, 28 and y29, at each end. As shown in FIG. 11, both inlet ports 26 and 27 are connected through check valves 28 and 29', respectively, to an inlet pipe 30 which leads to a reservoir for scavenge fluid represented schematicallyV at 31.

Another bore 32 extends through the body -1-1, the ends of which are also closed by end plates 8 and 9, which slidably receives therein the valve plunger 33 to dene a valve 34. The valve 34-has a pressure port 34a connected to pressure line 35. Motor driven pump 36 takes hydraulic fluid from Ithe sump 37 ocE the hydraulic system or' the machine anddelivers it to pressure line 35 at a pressure established by relief valve 36a connected to line 35 and discharging into sump 37. The valve 34 has a pair of discharge ports 38 and 39, one on each side of pressure port 34a, which are connected to a return line 40 by which Iiluid is returned to the sump 37.l The valve 34 has a'pair of motor ports 41 and 42, "each between the pressure port and one of the discharge ponts, connected, respectively, through lines 43 and 44 to inlet ports 22 and 20 of the motor chambers. The valve 34 also has a pair of terminal ports 45 and 46 in communication with the respective ends of valve plunger 33 and connected, respectively, through lines v47 and 48 to the outlet ports 21 and 23 of the Vmotor chambers. g

VThe valve plunger 33 reciprocates in response to pressure supplied alternately at terminal ports v45 and 46. The plunger has a spoo1 49 which moves from one side Vof the pressure port 34 to the other as'the plunger moves fromone extreme position tothe other. The" plunger 33 also has a pair of end spools 50 and 5-1 which alternately open and close discharge ports 38 and 39 as'fthe plunger reciprocates. The spool 50 ,is integral with plunger 33, and the spool 51 has an integralsleeve pinned to plunger 33 at 51u.` When lthe plunger 33 is in the right hand position, shown in FIG; 3, the pressure is' ccnl nectedthrough the valve to motor port 41 and 'is blocked, or disconnected, from motor port 42, `whichvat l,that time is connected to' discharge port 39. Conversely, when the valve plunger 33 is' in the extreme left hand position the pressure poi-t is connectedyto motor pont42 and disconnected from motor port'41, which is then connected to discharge port `38. .As the spool 49 passes'overV and blocks the pressure port 34a a dead center-'position is reached. Where the pressure is blocked from? the motor ponts. Therefore, pressure is blocked fromthe .terminal port at -which pressure was,` previously v`supplied to move the valve. Unless the valve plungerY is kept moving past this dead center position by some other force the reciprocating pistons in the motor chambers 15 andt16wi1l stall, and the'valve plunger will remain at the dead center position. Rather than relyon'the momentum of the Patented Jan. `9, V11362 3 valve plunger to carry it past this position it is preferable to provide a positive acting actuator to prevent stalling.

To this end the valve plunger 33 has a pair of oppositely beveled surfaces 52 and 53- which are joined at an apex 54. Bores 55 in communication with bore 32 have plugs 56 at their outer end and balls 57 at their inner ends, the balls defining actuators urged into engagement with the valve plunger 33 by springs S8. When the balls engage surface 52 the plunger is urged to the right; when the balls engage surface 53 the plunger is urged to the left. It will'. benoted that the bores 55Vare connected to the discharge line 40 to prevent trapped fluid which leaks past the balls from blocking the yielding-movement of the balls.

If the spool 49 were fixed on the plunger33 and spaced from apex 54 an amount equal to the distance between the center of the actuators 57 and the center of pressure port 34a, the balls 57 would be engaged with the apex 54 as the spool 49 reachesthe dead center position and the. actutators might not Ibe effective to carry the spool past dead center. In order to assure that the balls are engagedyvith the beveled surface behind the apex (relative totheldirection of movement) as the spool 49 passes.

the pressure port, regardless of the direction of movement of the plunger, the spool 49 is loosely received on Ythe plunger and shiftable thereon between a position where the spool 49 abuts against xed shoulder 55 and a position where the sleeve 56 integral with spool 49, abuts against xed .shoulder S7. Y yIt will be. noted Ythat when the valve plunger is in its right hand position (as shown in FG'. 3.) the left side of the shiftable spool 49 is exposed. to pressure and the right side thereof is exposed to exhaust so the spool sleeve 56' is. held-aganst shoulder 57. Shortly after the spool 49 passes over pressure port- 34a duringmovement of the valve plunger 33. tothe left, discharge port` 38 opens and discharge .port 39 is closed so that the right side of spool 49 is exposed to pressure and theleft side thereof is exposed/to exhaust. This tires the spool 49 to the left on v valve plunger 33 against the fixed shoulder 55 thereof'. When the valve plunger 33 is moved to the right, the spool 49` is initially in its left hand position onvplunger 33 but, after passing. the pressure port, isred to its right hand position. where sleeve 56 engages shoulder 57 The extreme positions of the spool 49l on the valve Y plunger 33 are spaced from the apex 54 a'lesser and greater amount, respectively, than the distance between the pressure port and the actuators. Therefore, when the plunger begins movement to the left, the spool 49, which is in its rightV handV position on the plunger at that time, is spaced furtherV from the apex than the distance between'the pressureport' and Vthe actuators so that. the yapex passes the actuators before the spool 49 passes the pressure port. i Thus, when the spool reaches the dead center position the actutators are engaged withrthe beveled surface 53"and the. plunger is kept moving past the dead center position by the actuators. The actuators, aided bythehydranlic liningV of the spool 49 `against-the. lixed shoulder YiTSfon the valve plunger, keep the valve plunger movingl to its extreme left hand position.. When Vthe plunger beginsV return movement to the right, the spool 49 at'that. time .is inits left hand position .onY the plunger Y andV isispacedV from-.the apex, S4an amount less than'the Y distance. between the actuators and the pressureV port so Vthat theY apex passes the actuators before the` spool passes the pressure; port. Thus, when. the spool 'reaches dead i center thefaetuators are engaged with the beveled surface Y "om the valve` plunger' after the` spool passes the dead center position. It will be 'notedv that as the plunger moves initially froinits'ext'reme positions vthe balls are urged Y 4- beveled surface in front of the apex 54 (relative to the direction of movement).

In operation, with the valve 34 in the position shown, pressure is supplied through the valve to motor port 41, line 43, and inlet port 22 of motor chamber 116 to shift the piston rod 19 to the left. Fluid in motor chamber 15 is discharged through inlet port 20, line 44, motor port 42 of valve34, discharge port 39, and line 40'to sump 37 In chamber 24 scavenge fluid previously drawn into the left side of the chamber is discharged through outlet port 28. Port 23 has a line 58', containing check valve 59, connected thereto which leads to sump 37. At the same time, uid is drawn into the right side of chamber 24 from the reservoir 31 through pipe 30, check valve 29', and inlet port 27. As piston rod 19 approaches its extreme left hand position outlet port 23 of motor chamber 16 is uncovered. and ports 2-3 and 22 are thereby connectedV to supply pressure through line 48A to terminal port 46 of valve 34. This shifts valve plunger 33 to the left, spool 49 shifting to its left hand position on the plunger 33 after it passes the pressure port 34a. Fluid from the left hand'side of valve bore 32 is discharged through terminal port 45, line 47, .port 21 of motor chamber 15, chamber 24 and port 28 thereof, into line 58 and thence to sump 37.

When valve 34 shifts to the left, motor. port 41 is disconnected from pressure port 34a and motor port 42 is connected to port 34a. Thus', pressure is supplied to inlet port 20 through line 44, and piston rod 19 is shifted to the right. Fluid from chamber 16 is discharged through port 22, line 43, port 4I of valve 34, discharge port 38, and line 40 to sump 37; At the same time uid in the right hand end of chamber 24, which was drawxrin on the previous stroke, is discharged through port 29. Line 60, havingV check valve 61, is-connected to port 29 and eads to sump 37. Simultaneously, scavenge lluid is drawn in yto the left hand side of chamber 24 from. reservoir 31. through pipe 30, check valve 2S', and inlet port 26. At the end` of .the stroke the port 21 of motor chamber 15 is uncovered by piston 17, connecting that port to inlet port 20, and pressure is supplied through line 47 to terminal port 45, shifting the valve plunger 33,. once again, to the right hand position. Fluid from the right end of bore 32 is discharged through line 48, port 23, chamber 24, port 29, line 6i! and check valve 61 thereof, to sump 37. It will be noted, that with the construction ofthe present invention the chamber 24 can be of substantially greater diameter Vthan chambers 15. and 16 and liuid can vbe pumped from reservoir 31 to sump 3'7 on each stroke ,so that ,substantially more uid'can be returned to the system thaniis utilized. In the embodiment above described fluid is continuously pumped from a singlefreser- With the embodiment shown' incFIG.. 4, fluid can be pumped from two separate reservoirs,iluid being drawn from each on alternate strokes. To accomplish this the vacuum chamber inlet port 26 is'connectediorline 62 through check valve 63 while. the inlet. port V27 is connected to line 64V through'check valve 65. Line 62 leads from reservoir 66:,in Awhich scavenge fluid has been trapped, while line 64 leads from the separate reservoir 67 also containinglscavenge uid.

Although theV connecting lines between the valve'V 34 andthe motor chambers have `been shown schematically these Ilines may be drilledpassages in the body 11 and theen'df plates Sland 9.

Y What is claimed is: Y

' l. A scavenge pumpfcomprising: means defining a pair of 'motorchambers each having aninlet port at one endv and an outlet port spaced from the opposite end and eachY having .amortir piston movable a predetermined distance lin one `direion in response to .pressure atthe inlet port to uncover,v the outlet, port and` connectsaid inletl and outlet ports',` said motor pistons operatively sure alternately supplied to said inlet ports; means delining a vacuum chamber having an inlet port and an outlet port, said vacuum chamber having a piston operatively connected to the motor pistons and reciprocated `thereby to draw -scavenge fiuid in the vacuum chamber inlet port and to discharge fluid through the vacuum chamber outlet port; and a valve having a pressure port, a pair of motor ports in communication with the inlet ports of the motor chambers, respectively, and a pair of terminal ports in communication with the outlet ports of the motor chambers, respectively, said valve having a valve plunger slidably received therein having ends in communication with the terminal ports, said valve plunger having a pair of oppositely beveled surfaces thereon joined at an apex and having a spool shiftable thereon, the valve plunger shiftable in one direction in response to pressure at one terminal port from the outlet port of one motor chamber to connect the motor port in communication with the inlet of other motor chamber to the pressure port as the spool passes the pressure port and shiftable in the other direction in response to pressure at the other terminal port from the outlet port of said other motor chamber to connect the motor port in communication with the inlet port of said one motor chamber to the pressure port as the spool passes the pressure port, the spool shifting on the plunger in the direction yof plunger movement when the spool passes the pressure port, said valve having a spring urged `actuator adapted to engage the beveled surfaces of the valve plunger to assist movement of the valve plunger after the apex thereon has passed the actuator.

2. A scavenge pump comprising in combination: a valve having a pressure port and having a motor port and discharge port on each side of the pressure port, said valve having a pair of terminal ports and having a spring urged actuator therein; a valve plunger having a pair of oppositely beveled surfaces joined at an apex slidably received in the valve for reciprocation in response to a pressure differential at the valve terminal ports, said beveled surfaces adapted to engage the actuator for continued movement of the valve plunger by the actuator after the apex has passed the actuator, said valve plunger having a shiftable spool thereon and having spaced fixed shoulders defining two extreme positions of the shiftable spool on the valve plunger, the spool in one extreme position opening the pressure port to the motor port on one side of the pressure port when the apex is at the actuator and in the other extreme position opening the pressure port to the motor port on the other side of the pressure port when the apex is at the actuator, the spool shifted on each stroke of the valve plunger from one extreme position to the other by pressure at the pressure port as the spool passes the pressure port for positioning thereof in the extreme position to pass the pressure port on the next stroke after the apex has passed the actuator, said valve plunger connecting one motor port to the pressure port and the other motor port to a discharge port when the valve plunger is at one end of a stroke and connesting said other motor port to the pressure port and said one motor port to the other discharge port when the valve plunger is at the opposite end of a stroke; a pump body having a central pump chamber and two motor chambers one on each side of the pump chamber and in communication therewith, the pump chamber having an inlet port and an outlet port at each end, the motor chambers each having an outer end port connected, respectively, to the motor ports in the valve, the motor chambers each having an inner port spaced from the inner end of the motor chamber and connected, respectively to the valve terminal ports; a piston rod received in the body for reciprocation therein and having a piston slidably received in the pump chamber to draw in fluid alternately through the inlet ports at the ends of the pump chamber and simultaneously to discharge fluid alternately through the outlet ports as the piston rod is reciprocated, the piston rod having a piston slidably received in each motor chamber for reciprocation between predetermined extreme inner and outer positions in response to the pressure alternately supplied to the respective outer end ports of the motor chambers through the valve motor ports, the piston in each motor chamber uncovering the inner motor chamber port at both extreme positions, the inner ports communicating through the motor chambers respectively with the outer end ports thereof when the respective pistons are alternately in their inner positions to apply pressure alternately to the ends of the valve plunger, said inner ports communicating with an outlet port of the central pump chamber when the pistons are alternately in their extreme outer positions.

3. In a pump of the type having a pump piston with a reciprocating motor connected thereto, and having a valve with a pressure port connectable to a continuous source of fluid under pressure, said valve having a Valve plunger operable on reciprocation to alternately supply pressure from the pressure port to the respective sides of the pump motor for reciprocation thereof, said valve plunger reciprocated in response to reciprocation of the pump motor, mechanism to minimize stalling 0f the valve plunger as pressure from the pressure port is diverted from one side of the motor to the other comprising in combination; a pair of oppositely beveled surfaces on the valve plunger joining at an apex, an actuator in the valve and a spring to urge the actuator toward the valve plunger, the actuator'adapted to engage the beveled surfaces Of the valve plunger for compression of the spring as the apex approaches the actuator and expansion of the spring after the apex passes the actuator to assist movement of the valve plunger in the direction of travel after the apex has passed the actuator, a spool slidably received on the valve plunger for shifting thereon, a pair of spaced stops straddling the shiftable spool to define two extreme limits of movement of the spool on the plunger, one of said stops located on the plunger to define one extreme position of movement of the spool on the plunger on one side of the pressure port when the apex is at the actuator and the other of said stops located on the plunger to define the other extreme position of movement of the spool on the plunger on the other side of the pressure port when the apex is at the actuator whereby the spool is shifted by pressure at the pressure port in the direction of valve plunger movement on each stroke as the spool passes the pressure port and is therefore positioned to pass the pressure port after the apex has passed the actuator on the next reverse stroke.

References Cited in the file of this patent UNITED STATES PATENTS (2nd addition to No. 567,394)

Patent No. 3,016,016

January 9, 1962 Herman .Horlacher he above numbered patertiiied that error appears in t Patent should read as It is hereby c cation and that the said Lettere ent requiring corre corrected below.

Column l, line' 7l, for "inlet" read outlet signed and sealedxtvnis 8th day of May 1962.

(SEAL) Attest:

DAVID L. LADD ERNEST W. swIDER Attting CCI Commissioner of Patents 

